Dynamo-electric machine



2 Sheets-Sheet l.

(No Model.)

C. S. BRADLEY.

DYNAMO ELECTRIC MAGHNE. No. 390,489. Patented Oct. 2, 1888.

C. S. BRADLEY.

DYNAM@ BLEOTRIG- MAGHI 2 Sheets Sheet 2.

Patented Oct. 2, 1888.

UNITED STATES PATENT CHARLES S. BRADLEY, OF YONKERS, NEW YORK,

DYNAMOnELECTRiC iVlACHlNE.

SPECIFICATION forming part of Letters Patent No. 390,439, dated Ootcbet: 2, 1883.

Application filed May 9, 1357.

To all whom it may concern:

Be it known that I, CHARLES S. BRADLEY, of Yonkers, in the county of Testchestcr and State of New York, have invented certain new and useful Improvements in DynamolElectric Machines, of which the following is aspecification.

In alternating-current machines as heretofore constructed the generation of current occurs for' practically half the time only, as there are certain points in the revolution ofthe armature at which the maximum potential is generated, but between these points of maximum there are an equal number of points of zero potential. This fact arises from the modern construction of alternating-current machines wherein a multipolar field-magnetis ordinarily used with a drum-armature having windings or coils laid on its external surface. These coils and theirarrangement on the drum must bear a detinite relation to the number and angular separation ot' the pole-piece of the eldmagnet, and the result is that there are a number of blank spaces on the surface of the armature not occupied by coils and therefore not utilized for the production of current, as will be more clearly understood further on.

For some purposes it is desirable that the machine should be capable of giving oil' either a continuous or an alternating cnrrent,or both, at will,and give the maximu 1n amount of either or both kinds of current with the maximum efficiency.

The objects o1p my invention are therefore, among others, to overcome the described diiticulties and limitations, to increase the capacity ofoutputofalternating-currentdynamos,andto vconstruct a machine which will generate either an alternating current or a continuous current, or both, as desired, and will give either or both with the maximum efficiency and outn put.

To thisand other ends my invention consists in the machine and its arrangement and combinations ot' circuits and devices,as hereinafter fully described and claimed.

In the accompanying dia\vings,which ilius trate my invention and form a part of this speeication, Figures l, 2, 3, et, 5a, Gil, and 7 represent the characteristics of my invent-ion diagrammatieally. Fig. l is a simple diagram .representing my principle of increasing the Serial No. 237,515. (No model.)

capacity for output of alternating-eurrent dynamos as applied to a simple two-pole machine. Fig. 2 is a diagram representing the manner of connecting a closed-circuit armature to give alternating currents according to my invention. Fig. 3 is a diagram representing the manner of connecting an armature to give both continuous and alternating currents while adhering to my fundamental principle. Fig. 4 is a plan view of a dynamo constructed according to myinvention. Fig. 5 is a detail View in section showing the continuouscun rent commutator and the alternatingcurrent contact-rings, and the manner of connecting the same. Fig. Gis a set ot' diagrams of the two curves produced by Fig. l, illustrating the relative periods of alternation produced by the machine constituted according to my invention, and making clear the effect ol' such on the total capacity ofthe machine itself.

N and S represent, respeetivelygthe north and south pole pieces ofthe ield-magnet,which may be excited by a separate current or in any suitable manner.

A is the armature-core, and B the winding Ofa simple Gramme ring, which will serve for my illustration. Connections are assumed as being made to the winding at four equidistant points by the terminals C, F, D, and E, arranged in the order named, so that C and D will be at diametrically-opposite points, and E and F similarlygbut on a line at right angles to the line of@ and D.

Assuming the armature to be revolving,and considering the successive actions therein according to the well-known laws of induction, the terminals G and D are, in th e position of Figi, at the maximum diii'erence ot' potential, and if they be connected together directly or through any external resistance current will liow and will be maximum for the resistance ofthe said circuit. The terminals and F on the contrary at this moment are eaeh at a common potential and of like sign, and consequently as there is no difference of potential exist-ing between them no current would flow through any circuit connecting them together.

Figa? represents the same armature, with the terminals C, F, D, and E connected to fourdil'- ferent contact-rings of d e, respectively. For

the sake of clearuess these rings are shown as concentrically arranged one within the other IOO in the same plane. Two brushes applied to the contact-rings c and d, respectively, will take off an alternating current from the armature. This current when the armature is in the position indicated in the figure would be at a maximum in one direction, or, say, above zero; when the armature has revolved through ninety degrees, this current from C D would be zeroat one hundred and eighty degrees it ro would be at a maximum in the opposite direction, o r, say, below zero, at two hundred and seventy degrees it would again be zero, and so on through each revolution of the armature. If now two other brushes be applied to the i5 rings e andf, respectively, a similar and equal alternating current will be taken from them; but this second current will differ from the first in time by exactly a quarter of a phase or wave-length-that is, when the first current 2o or C D is at a maximum the second orE F will be zero, and, conversely, when the first is zero the second will be at a maximum. This will be clearly understood by inspection of Figs. I to 7, inclusive.

Figs. l"h te a show the armature at four different positions, each ninety degrees from its predecessor. In Fig. IL the terminals C D are at a maximum difference of potential in one direction-say positive-*while E F are each of 3o the same potential and the same sign, andare therefore at zero so far as concerns the delivery of current externally In Fig. 2, CI) are of the same sign and potential, and' therefore at zero, while E F are now at a maximum dif` ference of potential positive. At Fig. 3, C D are at a maximum difference of potential in the opposite direction or negative, while E F are at zero, and in Fig. 4, E F are now ata maximum difference of potential negative, 4.o while C D are at zero. rlhe resulting diagrams of output may be graphically shown, and Fig. 5 represents the periodic phases of o utput from the terminals C D. while Fig. 6a shows the corresponding phases 'of output from the terminals E F, the dotted vertical lines indicating each oue-quarterof aphase or wave-length, while in the particular relations of winding and pole-pieces shown they will also be indicative of each one-quarter revolution. rilhus in the case of any given armature I can effect the generation of two independent currents, eachr'supplementing the other in the manner above described, and thus the time wasted during the generation of one is utilized forthe generation of the other, and therefore two currents are obtained from the same machine, eaeh of which is practically as great as the machine would generate if used in the ordinary way. These two currents can be cm- 6c ployed for any purpose to which alternating currents are applicable, and they may be used separately, one being used to feed one circuit andthe other to supply another circuit.

In Fig. 3 thearmature is represented as connected to a reetifying-commutator, K, in

the usual manner, and the same winding or armature conductor is connected to contactrings, precisely as in Fig. 2.

Fig. 4 shows in complete form a dynamo constructed and connected in this way, K being the rectifying-commutator, and c d efbeing the four contact-rings. I prefer to place the contact-rings c Z ef beyond the bearing L, as represented in Figs. 4 and 5, in order that the bearing shall not be placed too far out on the shaft. In this case the ring C is connected to one commutator-strip, while the ring D is connected to the commutatorstrip diametrically opposite; and the rings E and F are connected, respectively, to the two commutatorestrips occupying positions ninety degrecs either way from the strips to which the rings C and D are connected. The connections from the commutator-strips to the rings are carried through the shaft, which is made hollow for that purpose, as shown in Fig. 5. Vith such construction and arrangement, on revolving the armature of the machine a coutinuous currentmay be taken from the commutator K by suitable brushes in the usual manner, one alternating current may be taken from the rings C and I), and another alternating current may be taken from the rings E and F; but, as hereinbcfore explained, this second alternating current will be a quarter of a phase behind the current taken from the rings C D. These currents may all be taken at the same time, if desired, and their relative proportions to each other will depend upon the external resistances in the three circuits, in accordance with well-known laws.

The advantage of a dynamo constructed according to my invention is that it may be used either as a conti n nous current machine, oras an alternating-current machine, or both. W`hen used as a contiimous-current generator, it is justas good as if specially made for continuous currents. If used as an alternating-cnrrent generator, it is much better than the machines now generally employed on account of the large increase of output possible with a given size ofmachine. Ithus have a dynamo which can be used for either purpose; and at any time the owner or-user desires to change the alternatingcurrent system to the continuous, or vice versa, he can do so without any trouble whatever.

Another advantage from the foregoing construction lies in the fact that when the machine is used as an alternating-current generator a continuous current for energizing the field-magnets can be taken from the continuuous-currcnt commutator*or,in other words, the machine is in that event self-exciting.

Any approved form of armature can be connected up according to my invention. For ex IOO ample, a drum-armature may be connected in a manner precisely similar to that which I have shown and described for a Gramme ring. The form of armature and its winding, described by H. Muller in United States Patent No. 331,726, is also well adapted for connection and use in this manner. I prefer to employ those forms of armature in which the winding is so constituted as to form what is known as a closed circuit in preference to an armature whose Winding is in the form of one or more open-ended coils, because the fornier are generally of higher efficiency and output, and are, besides, much more conveniently applicable to my purpose.

It is obvious from inspection of Figs. 3 and 4 that my machine may be used as a motor as well as a generator, and that it may, when so used, be fed or actuated either by continuous or alternating currents, or both. the continuons currents being fed through-the brushes of the rectifyin0-commutator K andthe alternating currents being supplied through the contact-rings c d ef. It is also obvious that my machine may beused as a device for changing` a continuous current to an alternating current, or vice versa. or one alternating current into another of different time phase. The former would be accomplished by feeding the machine with a continuous current by the brushes on the reetifyiiig-commutator, and an alternating` current or two alternating currents can be taken from the machine through the brushes in contact with the rings c, d, e, andf. Where alternating currents are to be delivered to the machine and by it commutated into continuous currents, the alternating currents will be delivered in the first instance through the rin'gs c, d, e, andjand the rectified continuous current will be taken off bythe ordinary bearing on the commutator K. Vhere it is desired to use the machine to change one alternating current into another of different time phase, the primary current is sent into the machine through the rings c d, for example, and from the rings ej' there can be collected an alternating current whose time period will differ by one-quarter phase from the original or primary current. When it is desired to usethe machine so constructed for any purpose which dees not involve the simultaneous use of both sets of brushes, the set which is not wanted is simply lifted out of contact with its rings or com nintator, as the case may be. For example, if the machine is to be used as a continuouscurrent generator only the brushes are applied to the rectifying-commutator l.

and all brushes bearing on contact-rings c d ef are lifted out of contact with such rings, so that there will be no circuit except the external circuit from the connnutator K through its own brushes. Conversely, when the machine isused as a generator for alternating currents alone the corresponding brushes are placed in contact with their rings c d ef, and the brushes, bearing on the rectifying-commutator K, are lifted out of contact therewith if the iield magnets are energized vfrom another source; butif the machine is to be self-exciting the brushes are left en the commutatorK and connected in the usual. manner with the energizing-coils ofthe iieldmagnet, and in this ease the resistance in the iieldniagnet circuit will be made high enough to absorb only the percentage of the total current proper for the pu rpose of charging the fields.

Many other modifications in the manner of use of such a machinel will readily suggest themselves to one skilled in the art to which this invention appcrtains, and the same need not be more speciiically referred to herein. In order to avoid confusion l use the term current-leading device as expressive of either rings and brushes or commutator and brushes, or both. according to the use and manner ol' use of the machine.

l claim as my inventionl. An alternating-current dynamo-elcctric machine having generative conductor, in combination with two pairs of current-leading devices, said pairs being respectively connected to the generative conductors, so as to collect two independent alternating currents, one of which has its time phase substantially oncfourth of a wave length or period behind the other.

J 2. An altornatiiig-current dynamo-electric machine constructed with its generating-cir cuit closed, in combination with two pairs of current-leading devices, the pairs being rcspectively connected to said generating-circuit, so to collect two currents independent of each other and substantially onefourth of a phase apart in their relative time-periods.

3. An alternatingmurrent dynamo-electric machine constructed with its generating-corr ductor constituting a closed circuit, and having two pairs of independent current-leading devices, one pair connected intousaid closed generatingcircuit at mutually opposite points, andthe other pair connected into said generatingcircuit at intermediate points also mutually opposite each other.

A dynamoelectric machine having an armature provided with a current-rectitying colnmutator and brushes thereler, and two pairs of current-leading devices, the pai being respectively connected to the armature winding at alternating points ofthe same, so as to lead oit two alternating currents independent of each other, and substantially one-fourth of a phase apart in their respective tiniclperiods.

5. An electro-motive device consisting of a field-magnet and a rotating armature provided with a rectiiying-commutator and brushes therefor, through which current is received into the armature and rotation produced, in combination with two pairs of currentdeading devices respectively connected to the armature winding at alternating points, and so ar ranged relatively as to lead off two independent alternating currents substantially one fourth of a phase apart in their relative time periods, whereby a continuous current maybe transformed into two independent alternating currentsE 6. An electromotivc device consisting cfa IOO ieldmagnet and a rotating armature provided with a rectifying conimutator and brushes therefor, in combination with two pairs of cnr rent-leading devices, each pair independently connected to said connnutator at respectively alternating points, and the two pairs adapted to receive and deliver to said armature two independent alternating currents of different phase from corresponding external circuits.

7. An electro motive device consisting of a field-magnet and a rotating armature provided with a rectifying commutator and brushes therefor in circuit with the field-magnet coils, in combination with two pairs of current-lead ing devices-suel1,for instance,as contact rings and brushes-each pair independently connected to the armature winding at alternating points of the same, substantially as described, whereby the two pairs of current-leading devices are adapted either to receive and deliver to said armatn re two independentalternating en rrents of differing phase from corresponding external circuits or to receive from one external circuit asingle alternating eurrent,ehange its time-period, and deliver the saine into another external circuit.

8. Aself-excitingalternate-currentdynamoelectric generator having a reetifying-commutator and brnshcs'connectcd toits ield-'lnagnct circuit and having two pairs of collecting rings and brushes adapted to deliver two independent alternating currents externally, the generating-circuit being common to both the com- Inutator and collecting rings.

9. A rotary electric motor consisting of a field magnet and armature and two pairs of current-leading devicesMsnch, for instance7 as contact rings and brushes-the respectivepai rs being independently connected into the armature winding at alternating points of the same and arranged for connection with two independent external circuits.

GHARLES S. BRADLEY.

Witnesses:

FRANCIS B. CnooKna, Unas. J. MAGUIRE. 

